Miles impact any RV.
We have a 2014 Flagstatt (36 ft) which has been from Texas to Key West to Maine to San Diego and a lot of places between in 39 months and 26,989.2 miles being towed.
We've had a couple problems including a weld failure on an axle - Dexter Axle QC issue.
We've had some things shake loose.
In general most of the full-times I see in the area east of the Rockies have a 32-36 foot long fifth wheel. Most farther west seem to go a bit smaller.
There really isn't a "full timers" TT brand. The folks who seem to have the fewest problems in my talks with them are folks in Castia or similar less than 20 ft eggshell trailers.
We can't live that way. We need our recliners, a decent sized bath, and our queen sized sleep number bed.
As mentioned above - TT have almost no external storage space, and usually have very little weight carrying capacity. Everyone I have met uses their truck/ tow vehicle as their primary storage for tools, outdoor gear, spare parts, etc.
Personally I wish our budget/ income would allow a 35-40 ft diesel pusher. But that ain't gonna happen. We might move to a 36-38 foot 5th wheel in a couple years if we can find the right used model.
My advice - get the best pickup you can afford with the best payload and towing capacity.
Get an affordable used TT that you can afford to sell trade in two years. And hit the road. If your first choice doesn't work out, you can change.
Only you and your significant other can decide if a layout/ rig works for you.
I will say that I get tired/ frustrated with the more complex process of setting up, preparing to tow the TT at times, especially when we are moving every couple days. Especially when traveling with friends with a Class A or Class C.
I also regret the poor fuel mileage. Not while towing. We get better mileage than a gas class A and some class C models. We get slightly less mileage than Class A dps.
It is the sight seeing and 'around the area' driving where my big pickup mileage bothers me.
In the near 27,000 miles towing, we have also driven almost 50,000 miles without the trailer.